UNIDENTIFIED gunmen stormed a pro-opposition newspaper office in Sri Lanka and set fire to the printing presses, police said.

More than a dozen armed men started the blaze after breaking into the Sunday Leader newspaper building - which is within a high-security air force complex on the edge of the capital Colombo - and forced the staff out, police said.

The paper's chief editor, Lasantha Wickrematunga, accused the Government of carrying out the attack. His newspaper has been highly critical of the administration of President Mahinda Rajapakse.

"It is a cowardly attack within a high-security zone by a regime that is acting like a terrorist organisation," Mr Wickrematunga said.

"What can you expect from a regime that is involved in human smuggling? We will prevail."

His paper has also accused the Government of providing a passport under a false name to a renegade Tamil Tiger guerrilla leader to enter Britain. The case has led to tension between Colombo and London.

A local rights group, the Free Media Movement (FMM), said it was outraged by the attack and held the Government responsible for failing to protect the publishing house.

"The culture of impunity that prevails in this country has prevented any meaningful inquiry into all acts of violence against media and journalists that have taken place under this Government," the group said in a statement.

There was no immediate reaction from the Government to the attack on the Sunday Leader. The paper's printing presses were also set on fire in October 2005 in the run-up to presidential elections.

The Government imposed blanket censorship last month, but rolled it back amid intense criticism from local and international media rights groups.